Slice the flank steak against the grain into thin, bite-sized strips and season with the sea salt and black pepper.
In a small glass bowl, whisk together the coconut aminos, rice vinegar, and toasted sesame oil to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips in a single layer and sear for approximately 2 minutes until browned, then remove the beef from the pan and set aside on a plate.
In the same pan, add the broccoli florets and sliced red bell pepper with a splash of water, then cover with a lid for 2 minutes to steam-soften.
Remove the lid, add the grated fresh ginger and minced garlic, and sauté for 1 minute until the aromatics are fragrant.
Return the cooked beef and any accumulated juices to the pan and pour the prepared sauce over the mixture.
Toss everything constantly for 1-2 minutes until the sauce reduces slightly and creates a glossy coating over the beef and vegetables.
In a separate small skillet over medium heat, lightly sauté the cauliflower rice for 3-5 minutes until tender and moisture has evaporated.
Plate the cauliflower rice, top with the beef and broccoli mixture, and garnish with sesame seeds before serving.